Short story anthologies are generally produced as genre-based or theme-based, which in either case creates diversity.
I invited my guest authors exclusively from theIndie Author Support and Discussion group, established on Facebook in 2014.
Given a common brief, it is uncanny where authors will draw inspiration from.
Having compiled several anthologies of my own work and with guest authors, I believe there is no greater diversity than a collection of stories from international authors.This combination of talent brings readers a wide spectrum of genres, styles, and story lengths.